The gains of cooperation in a fishery duopoly : the Namibian and South African deep water hake fishery

This study evaluates the potential gains of cooperation between South Africa and Namibia in the resource management of the valuable transboundary deep-water hake fish stock. By combining the game strategic Cournot model with the Gordon Schaefer bio-economic model, we develop a static model used to investigate strategic decisions in the duopoly when the countries 1) manage the stock as shared and act interdependently when maximising their profits within their Exclusive Economic Zone (a Cournot duopoly), and 2) act in terms of regional cooperation with joint management (Sole Owner harvesting). These equilibriums are compared with Open Access regulation and the alternative Stackelberg duopoly. Moreover, we examine the effects of changes in costs or catchability on the equilibrium solutions of efforts, harvest, stock and profits. The theoretical model is applied to the Benguela-fishery by calibrating a numerical model based on observed values of the historic stock abundance and harvest, and availiable observations of costs and efforts in the period 2007-2015. Main assumptions are symmetry in fleets and a uniformly distributed fish stock. First, in assuming that we are initially in steady state, we investigate equilibrium changes when moving from a current scenario to Cournot, followed by a move from Cournot to Sole Owner. Equilibrium effects of an increase in costs and catchability are studied, and the Stackelberg duopoly is dicsussed. Finally, the asymmetric Cournot is further explored by looking at equilibrium effects when countries differ in costs and catchability. The numerical findings suggest that there are potential gains of cooperation both in terms of 1) cooperation in stock research and managing the stock as shared (Cournot), and 2) active regional management (Sole Owner), when using pre-exploitation levels of the carrying capacity of the stock.M-ECO

Kernelization of Vertex Cover by Structural Parameters

In the NP-complete problem Vertex Cover, one is given a graph G and an integer k and are asked whether there exists a vertex set S ⊆ V (G) with size at most k such that every edge of the graph is incident to a vertex in S. In this thesis we explore techniques to solve Vertex Cover using parameterized algorithms, with a particular focus on kernelization by structural parameters. We present two new polynomial kernels for Vertex Cover, one parameterized by the size of a minimum degree-2 modulator, and one parameterized by the size of a minimum pseudoforest modulator. A degree-2 modulator is a vertex set X ⊆ V (G) such that G-X has maximum degree two, and a pseudoforest modulator is a vertex set X ⊆ V (G) such that every connected component of G-X has at most one cycle. Specifically, we provide polynomial time algorithms that for an input graph G and an integer k, outputs a graph G' and an integer k' such that G has a vertex cover of size k if and only if G' has a vertex cover of size k'. Moreover, the number of vertices of G' is bounded by O(|X|^7) where |X| is the size of a minimum degree-2 modulator for G, or bounded by O(|X|^12) where |X| is the size a minimum pseudoforest modulator for G. Our result extends known results on structural kernelization for Vertex Cover.Master i InformatikkMAMN-INFINF39

Exploiting graph structures for computational efficiency

Coping with NP-hard graph problems by doing better than simply brute force is a field of significant practical importance, and which have also sparked wide theoretical interest. One route to cope with such hard graph problems is to exploit structures which can possibly be found in the input data or in the witness for a solution. In the framework of parameterized complexity, we attempt to quantify such structures by defining numbers which describe "how structured" the graph is. We then do a fine-grained classification of its computational complexity, where not only the input size, but also the structural measure in question come in to play. There is a number of structural measures called width parameters, which includes treewidth, clique-width, and mim-width. These width parameters can be compared by how many classes of graphs that have bounded width. In general there is a tradeoff; if more graph classes have bounded width, then fewer problems can be efficiently solved with the aid of a small width; and if a width is bounded for only a few graph classes, then it is easier to design algorithms which exploit the structure described by the width parameter. For each of the mentioned width parameters, there are known meta-theorems describing algorithmic results for a wide array of graph problems. Hence, showing that decompositions with bounded width can be found for a certain graph class yields algorithmic results for the given class. In the current thesis, we show that several graph classes have bounded width measures, which thus gives algorithmic consequences. Algorithms which are FPT or XP parameterized by width parameters are exploiting structure of the input graph. However, it is also possible to exploit structures that are required of a witness to the solution. We use this perspective to give a handful of polynomial-time algorithms for NP-hard problems whenever the witness belongs to certain graph classes. It is also possible to combine structures of the input graph with structures of the solution witnesses in order to obtain parameterized algorithms, when each structure individually is provably insufficient to provide so under standard complexity assumptions. We give an example of this in the final chapter of the thesis

Spinoffs in the Nordics : An Empirical Study of Value Creation in the Nordic Countries

This thesis investigates the long-term value creation of Nordic spinoffs from 1990 to 2022. First, we perform a long-run event study of spinoffs, parent firms, and proforma firms to conduct whether these firms create value in the long run. Moreover, we study the value creation factor focus to determine whether the value creation happens because of increased corporate focus. Additionally, we study the operating performance using a difference-in-differences model. In both models, we have compared spinoffs, parent firms, and proforma firms to matching firms using a propensity score matching model. In our analysis, we find statistically significant evidence that spinoffs outperform the matching portfolio by 30% over a three-year event window. Parent firms outperform the matching portfolio by 8%. However, it is not significant at conventional levels. Moreover, we find evidence that focus-increasing firms outperform non-focus-increasing firms over a three-year window, indicating that some of the value creation is due to increased corporate focus. Furthermore, our difference-in-difference (DiD) models indicate that the operating performance for spinoffs, parent firms, and proforma firms is better than their corresponding matching portfolios over the same three-year event window. We find statistically significant results for all performance metrics in the DiD model for the DiD-estimator, except for the first and second year of ROA and the third year of current ratio. Moreover, for the parent firms, we find no statistically significant results. For the proforma firms, we only find statistically significant results for return on assets and leverage in the first year. However, for spinoffs, the DiD results indicate reciprocal results between the event study models and the DiD models, meaning we can interpret the results economically. To sum up, our findings indicate that spinoffs create shareholder value in the long term, while the results for parent and proforma firms are more ambiguous.nhhma

Det norske Private Equity-markedet : har Private Equity-fondenes tilnærming til porteføljeselskapet før investeringsbeslutningen foretas endret seg etter finanskrisen?

I denne oppgaven har vi sett på hvordan finanskrisen har påvirket Private Equity-fondenes tilnærming til porteføljeselskapet, ved å ta utgangspunkt i evalueringskriterier bransjen benytter seg av ved seleksjon av bedriftene. I kartleggelse av etablerte evalueringskriterier har vi studert tidligere litteratur på området for å finne fram til hvilke kriterier Private Equity-fondene vurderer porteføljeselskapet ut fra. Videre har vi utformet en spørreundersøkelse, som vi har sendt ut til alle Private Equity-fond registrert hos Norwegian Venture Capital Association (NVCA) per mai 2011. Vi har valgt å ta utgangspunkt i aktører registrert hos NVCA på grunn av at vi dermed kan i større grad anvende rapporteringen i NVCA sine aktivitetsrapporter som sparringspartner når datamaterialet fra PE-fondene tolkes. Videre har vi hatt intervju med Argentum, hvor vi både fikk bekreftet, avkreftet og diskutert tendensene i det norske Private Equity og forløpet frem til i dag. I drøftelsen har vi utført blant annet regresjonsanalyse for å studere hvordan Private Equity-markedet påvirkes av økonomiske konjunkturer, og dernest utformet en faktoranalyse for å identifisere dimensjoner Private Equity-aktørene vurderer som mer viktig i forhold til seleksjon av porteføljeselskap nå, kontra før, finanskrisen. Krysskorrelasjonsanalyse anvendes for å kartlegge hvordan respondentene besvarer ulike spørsmålskriterier. Våre resultater tenderer til at Private Equity-aktørene gir økt viktighet til hovedsakelig tre faktorer, hvilke er nåværende virksomhet, tiltro til produktet og markedsrisiko. Vi finner også at resultatene våre korresponderer til en viss grad overens med tidligere studier, samt at det tenderer til at Private Equity-aktørene angir større viktighet til evalueringskriterier, som litteraturen angir som viktige

Rettsfølgene ved brudd på avtaleloven § 38 b - Forholdet mellom avtalerettslig ugyldighet og kontraktsrettslige misligholdsbeføyelser, herunder heving, ved brudd på opplysningsplikt i forbrukerforhold

Oppgaven omhandler forholdet mellom avtalerettslig ugyldighet og kontraktsrettslig heving ved brudd på opplysningsplikt i forbrukerforhold, særlig i tilfeller av brudd på informasjonsplikten etter avtaleloven § 38 bMasteroppgaveJUS39

Mim-Width III. Graph powers and generalized distance domination problems

We generalize the family of (σ,ρ) problems and locally checkable vertex partition problems to their distance versions, which naturally captures well-known problems such as Distance-r Dominating Set and Distance-r Independent Set. We show that these distance problems are in XP parameterized by the structural parameter mim-width, and hence polynomial-time solvable on graph classes where mim-width is bounded and quickly computable, such as k-trapezoid graphs, Dilworth k-graphs, (circular) permutation graphs, interval graphs and their complements, convex graphs and their complements, k-polygon graphs, circular arc graphs, complements of d-degenerate graphs, and H-graphs if given an H-representation. We obtain these results by showing that taking any power of a graph never increases its mim-width by more than a factor of two. To supplement these findings, we show that many classes of (σ,ρ) problems are W[1]-hard parameterized by mimwidth + solution size. We show that powers of graphs of tree-width w − 1 or path-width w and powers of graphs of clique-width w have mim-width at most w. These results provide new classes of bounded mim-width. We prove a slight strengthening of the first statement which implies that, surprisingly, Leaf Power graphs which are of importance in the field of phylogenetic studies have mim-width at most 1.publishedVersio

Overactive, aggressive, disruptive and agitated behavior associated with the use of psychotropic medications in schizophrenia

Background Evidence is limited for the associations between use of psychotropic medications and overactive, aggressive, disruptive or agitated behavior (OADA)1 in clinical practice. Aims To investigate the associations between risk of readmission with OADA and use of antipsychotics, antidepressants, mood stabilizers and benzodiazepines in patients with schizophrenia. Method A consecutive total cohort diagnosed with schizophrenia (N = 663) after admission to the Haukeland University Hospital psychiatric acute unit in Bergen, Norway, was followed from discharge over a 10-year period. At every following readmission, the level of OADA was assessed using the first item of the Health of the Nation Outcome Scale (HoNOS). Periods of use versus non-use of antipsychotics, antidepressants, mood stabilizers and benzodiazepines were recorded as time-dependent variables in each patient and compared using Cox multiple regression analyses. Results A total of 161 (24.3 %) patients were readmitted with OADA, and the mean (SD) and median times in years to readmission with OADA were 2.8 (2.6) and 2.1, respectively. We found that the risk of readmission with OADA was negatively associated with use of antipsychotics (adjusted hazard ratio (AHR) = 0.33, p < 0.01, CI: 0.24–0.46) and antidepressants (AHR = 0.57, p = 0.03, CI: 0.34–0.95), positively associated with use of benzodiazepines (AHR = 1.95, p < 0.01, CI: 1.31–2.90) and not significantly associated with use of mood stabilizers. Conclusions Use of antipsychotics and antidepressants is associated with reduced risk of readmission with OADA whereas benzodiazepines are associated with an increased risk of readmission with OADA in patients with schizophrenia.publishedVersio

Use of Benzodiazepines and Antipsychotic Drugs Are Inversely Associated with Acute Readmission Risk in Schizophrenia

Purpose: Little is known about the impact of different psychotropic drugs on acute readmission risk, when used concomitantly in a real-life setting. We aimed to investigate the association between acute readmission risk and use of antipsychotic drugs, antidepressants, mood stabilizers, and benzodiazepines in patients with schizophrenia. Methods: A cohort study included all patients diagnosed with schizophrenia admitted to a psychiatric acute unit at Haukeland University Hospital in Bergen, Norway, during a 10-year period (N = 663). Patients were followed from discharge until first readmission or censoring. Cox multiple regression analyses were conducted using antipsychotic drugs, antidepressants, mood stabilizers, and benzodiazepines as time-dependent variables, and periods of use and nonuse were compared within individual patients. Adjustments were made for sex, age at index admission, and excessive use of alcohol and illicit substances. Results: A total of 410 patients (61.8%) were readmitted during follow-up, and the mean and median times in days to readmission were 709 and 575, respectively. Compared with nonuse, the use of antipsychotic drugs was associated with reduced risk of readmission (adjusted hazards ratio, 0.20; P < 0.01; confidence interval, 0.16–0.24), and the use of benzodiazepines was associated with increased risk of readmission (adjusted hazards ratio, 1.51; P < 0.01; confidence interval, 1.13–2.02). However, no relation to readmission risk was found for the use of antidepressants and mood stabilizers. Conclusions: We found that use of benzodiazepines and antipsychotic drugs are inversely associated with acute readmission risk in schizophrenia.publishedVersio